instruction manual composite-arf yak 55sp, 3m · instruction manual composite-arf yak 55sp, 3m tavs...

[email protected] YAK 55SP (3m span)

Instruction ManualComposite-ARF YAK 55SP, 3m

TAVS Technology Version: 1.0

Instructions for YAK 55SP AirplaneThank you very much for purchasing our Composite-ARF YAK 55SP all composite aircraft, madeusing Total Area Vacuum Sandwich (TAVS) technology. It is based on our original 3.3m versionof the Yak, but reduced in size to better suit the most popular 150cc engine sizes, and now hasa standard 50mm diameter 6061 alloy wing tube which saves weight and simplifies storage andtransport.

Note: Version 1 Instructions only reflects the changes in the wings, so that Customers have thechoice of installing 2 or 3 servos (Futaba or JR) for each aileron - instead of only the 2 very pow-erful JR servos that were recommended in the ‘Preliminary’ instructions for the first few kits. Thehardware pack for the wings now includes the phenolic mounting plates and additional linkageparts required for both makes of servo (see page 7 for servo details). There are no other changesto the instructions.

You will notice that the photos in this instruction manual show both ‘Butterfly’ color schemes, andthat the prototype has some fibreglass balsa sandwich parts in the cockpit area - whereas theproduction versions have carbon composite-sandwich parts in the complete fuselage.

Before you get started building and setting-up your aircraft, please make sure you have readthis instruction manual several times, and understood it. If you have any questions, pleasedon’t hesitate to contact us. Below are the contact details:

Email: [email protected] [email protected]: Phone your C-ARF Rep!!! He will be there for you.Website: http://www.composite-arf.com

Liability Exclusion and DamagesYou have acquired a kit, which can be assembled into a fully working R/C model when fitted outwith suitable accessories, as described in the instruction manual with the kit.

However, as manufacturers, we at CARF-Models Co. Ltd. are not in a position to influence theway you build and operate your model, and we have no control over the methods you use toinstall, operate and maintain the radio control system components. For this reason we areobliged to deny all liability for loss, damage or costs which are incurred due to the incompetentor incorrect application and operation of our products, or which are connected with such opera-tion in any way. Unless otherwise prescribed by binding law, the obligation of the CARF-Modelscompany to pay compensation is excluded, regardless of the legal argument employed.

This applies to personal injury, death, damage to buildings, loss of turnover and business,interruption of business or other direct and indirect consequent damages. In all circumstancesour total liability is limited to the amount which you actually paid for this model.

BY OPERATING THIS MODEL YOU ASSUME FULL RESPONSIBILITY FOR YOUR ACTIONS.

It is important to understand that CARF-Models Co., Ltd, is unable to monitor whether youfollow the instructions contained in this instruction manual regarding the construction, operationand maintenance of the aircraft, nor whether you install and use the radio control systemcorrectly. For this reason we at CARF-Models are unable to guarantee or provide acontractual agreement with any individual or company that the model you have made will

Composite-ARF YAK 55SP (3m span) [email protected]

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function correctly and safely. You, as operator of the model, must rely upon your own expertiseand judgement in acquiring and operating this model.

Supplementary Safety NotesPre-flight checking:Before every flying session check that all the model’s working systems function correctly, and besure to carry out a range check.

The first time you fly any new model aircraft we strongly recommend that you enlist the help ofan experienced modeller to help you check the model and offer advice while you are flying. Heshould be capable of detecting potential weak points and errors.

Be certain to keep to the recommended CG position and control surface travels. If adjustmentsare required, carry them out before operating the model.

Be aware of any instructions and warnings of other manufacturers, whose product(s) you use tofly this particular aircraft, especially engines and radio equipment.

Please don’t ignore our warnings, or those provided by other manufacturers. They refer to thingsand processes which, if ignored, could result in permanent damage or fatal injury.

Attention !This model aircraft is a high-end product and can create an enormous risk for both pilot andspectators, if not handled with care, and used according to the instructions. Make sure that youoperate your Yak according to the AMA rules, or those laws and regulations governing the modelflying in the country of use.

The engine, servos and control surfaces haveto be attached properly. Please use only therecommended engines, servos, propellers,and accessories supplied in the kit.

Make sure that the ‘Centre of Gravity’ is locat-ed in the recommended place. Use the noseheavy end of the CG range for your first flights,before you start moving the CG back to a morecritical position for 3D-maneouvers. If you findthat you need to relocate your batteries oreven add weight in the aircraft to move the CGto the recommended position, please do soand don’t try to save weight or hassle. A tailheavy plane, in a first flight, can be an enormous danger for you and all spectators. Fix anyweights, and heavy items like batteries, very securely to the plane.

Make sure that the plane is secured properly when you start the engine. Have at least 2 helpershold your plane from the tail end, or from behind the wing tips, before you start the engine. Makesure that all spectators are behind, or far in front, of the aircraft when running up the engine.

Make sure that you range check your R/C system thoroughly before the first flight. It is absolute-ly necessary to range check your complete R/C installation first WITHOUT the engine running.


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NO !!!

Secure the planebefore starting the engine.DANGER ZONES

NO NO


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Leave the transmitter antenna retracted, and check the distance you can walk before ‘fail-safe’occurs. Then start up the engine, run it at about half throttle and repeat this range check with theengine running. Make sure that there is no range reduction before ‘fail-safe’ occurs. Only thenmake the 1st flight. If you feel that the range with engine running is less then with the engine off,please contact the radio supplier and the engine manufacturer and DON’T FLY at that time.

Check for vibrations through the whole throttle range. The engine should run smoothly with nounusual vibration. If you think that there are any excessive vibrations at any engine rpm’s, DON’TFLY at this time and check your engine, spinner and propeller for proper balancing. The light-weight sandwich composite parts don’t like too much vibration and they can suffer damage. Thelow mass of all the parts results in a low physical inertia, so that any excess vibrations can affectthe servos and linkages.

Make sure that your main and stab tubes are not damaged. Check that the front and rear anti-rotation pins for the wings and horizontal stabiliser are located correctly in their holes, and arenot loose. Check that the 4 plastic wing retaining nuts are tight, that the M3 bolts retaining thehorizontal stablisers on to the aluminium tube are installed and tight, and that the hinge tubes forthe rudder and elevators cannot come out.

If you carefully checked all the points above and followed our advice exactly, you will have a safeand successful first flight - and many hours of pleasure with your Composite-ARF Yak.

General information aboutfully-composite aircraft structure and design

All the parts are produced in negative molds, manufactured using vacuum-bagged sandwichconstruction technology. All parts are painted in the moulds, either single colour or designercolour schemes. A revolutionary production method, called TAVS (Total Area Vacuum Sandwich),enables us to present this aircraft with incredible built-in strength, while still being lightweight,and for a price that nobody could even consider some years ago. This production process hashuge advantages, but a few disadvantages as well. These facts need to be explained in advancefor your better understanding.

Description of Parts

The Wings:Both wing halves are made in negative moulds, fully vacuum-bagged, using only 2 layers of clothin combination with a hard 2mm foam sandwich to form a hard and durable outer skin. Becauseof this TAVS technology no additional structural parts are needed except for the main spar tube.

The ailerons are already hinged for you. They are laminated in the wing mould and are attachedto the main wing with a special nylon hinge-cloth, sandwiched between the outer skin and thefoam. This nylon hinge is 100% safe and durable. You never have to worry about breaking it, orwearing it out. There is no gap at all on the top wing surface, and there is a very narrow slot inthe bottom surface, where the aileron slides under the main wing skin during down throw. Thishinge setup is the cleanest you can ever obtain, but you have to take some care during assem-bly for proper installation and servo set up.

First, the hinge line is on the top surface of the wing, not in the centre. This is NOT a disadvan-

tage, if you set in about 10% NEGATIVE aileron differentialin your transmitter program. This means that the ‘down’throw needs to be about 10% more than the up throw.

Why? Because the axis of the hinge is not at the centrelineof the aileron, so it moves slightly in and out when it trav-els, and the aileron gets a little "bigger" in surface areawhen moving up, and "smaller" when moving down. This iswhy you have to set the negative differential in your trans-mitter to compensate for the size changing. 10% is a goodstarting point, and you will find out the exact setting during the first flights, doing fast vertical rollsand watching the fuselage rolling in a perfect line. You can set it perfectly, this is guaranteed.

The bottom slot needs some explanation, too. The cut line is exactly in the correct position sothat the aileron slides under the wing skin smoothly. If the cut was a few mm forward or back, itwould not work properly. So, make sure that the lip is not damaged, and that the aileron slidesunder this lip perfectly. It will NOT lock at any time, as long as the lip is not damaged. If damageoccurs to the lip, you can cut off 2-3 mm, but you should never need to cut off more than this.

The wings are already set-up with servo mounts milled in the plywood ribs, and a milled servoaccess hatch for the outer servos, and we recommend a pair of high-torque digital servos (eg:JRDS8511 or 8611) in each wing. Our servo covers and milled plywood mounts make installation,and exchange if necessary, very quick and easy and provide a rock solid servo mounting andlinkage system.

The wings are attached to the fuselage with the 4threaded aluminium dowel anti-rotation pins, with4 plastic nuts inside the fuselage. If the aluminiumdowels come loose in the wing, the wing will slideoutwards, away from the fuselage, and the mainspar tube will definitely break. So take great careto inspect the glue joints of these anti-rotationdowels in the wing REGULARLY. Excessive vibra-tions or hard shocks can cause the glue joints toweaken or break. Monitor these joints wheneveryou assemble your plane before flying it. Neverforget to tighten the nuts inside the fuselage. Please DONOT modify these attachment dowels in any way, their per-fect function is proven for many years.

The Fuselage: The fuselage is also made in negative moulds, and is allconstructed using TAVS technology. All the loadbearinginternal parts are installed during manufacture, to ensureaccurate location and reduce your assembly time. Thefibreglass tubes in the wings and stabs to receive the spartubes, and the anti-rotation dowels, are already installed.There is no need to even check the incidences - you can beassured that these are already set in the moulds so that noadjustment is necessary.The landing gear mount is strong and doesn’t need anyextra reinforcement. The fuselage is extremely light weight,and the gear loads need to be led into the structure gently.


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Centreline of hinge axis

Phenolic control horn

(above) The internal wing struc-ture, showing the carbon rovingand cloth reinforcement.(below) The wing root, showingthe 50mm Ø 6061 alloy wing tubeand the aluminium anti-rotationdowels in the root rib.

No glue joint needs to be stronger than the materials that itis attached to, as it would just result in increased weight forno advantage. The landing gear is a well proven design,taken from our 3.3m Yak, and the slight flexibility helps tosmooth any less-than-perfect landings. Do not change ormodify it, as the results would only be negative. We hadplenty of time and experience to engineer the strengthneeded in this area - and we did !

The motordome, firewall and molded exhaust system tun-nel are a fully integral parts of the fuselage, and provideplenty of strength for any engines up to 170cc on the mar-ket today. See the Engine Installation section for details ofengine and setting thrust angles.

The Stabilisers:The stab parts are also vacuum bagged sandwiched. Therudder and the elevator control surfaces are hinged with4mmØ tubes, fitted through phenolic hinge bearing plateswhich are jig-installed during manufacture for perfect align-ment.

The rudder and elevator design allows for at least 45degrees throw. For the Yak it is mandatory that the tail areais extraordinarily light weight, so the stab is designed for onepowerful digital servo installed in each half. All the structuralparts are preinstalled. The horizontal stabs are mounted withone 20mm aluminum tube and one 10mm carbon anti-rota-tion pin each.

Servo Screws:Fix all the servos into the milled plywood servo mountsusing the 2.9 Ø sheet metal screws provided in the kit, notthe standard screws normally supplied with servos by theservo manufacturer. This is because all the holes in ourmilled servo mounts are 2mm diameter, due to our CNCmanufacturing process, and this is too big for the normalscrews.

All stabiliser and aileron servos must be secured into 6mmthick plywood mounts, and we have included plywood dou-blers for you to add in any places where there is only 1layer of 3mm plywood present.

Take Care: Composite sandwich parts are extremely strong, but fragile at the same time. Always keep inmind that these contest airplanes are designed for minimum weight and maximum strength inflight. Please take care of it, especially when it is being transported, to make sure that none ofthe critical parts and linkages are damaged. Always handle your airplane with great care, espe-cially on the ground and during transport, so you will have many hours of pleasure with it.


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(above) The lightweight fin-posthas the phenolic rudder hingeposts already installed and alignedat the factory. The correspondingtubes are also installed in the rud-der for the hinge tube.(below) The elevator and rudderhinging uses 4mm diameter tubes,inside phenolic hinge posts thatare factory-installed and aligned.

AccessoriesBelow are the things you may need to get your Composite-ARF Yak 55SP in the air. Some ofthem are mandatory, some of them can be chosen by you. What we list here are highly recom-mended parts, and have been thoroughly tested.

1. Power servos (9 - 11 required). The elevators are specifically designed to have a single JR 8711 or JR8811 fitted into each, and we strongly recommend that you do not substituteany other servo (eg: JR8411/8511/8611) for these control surfaces. For Futaba users a single S9152 should be fine for each elevator, and mounting plates for these are included.We do not recommend fitting single S9351’s in the stabs for the elevators.

We highly recommend that the rudder is controlled by three JR 8511/8611 (or better) servos. Futaba users can install 3 x S9152’s, which also fit in the rudder tray.

You have a choice of 2 or 3 servos for each aileron, depending on the servos used, whichshould be installed in the phenolic mounting plates provided. JR users can install either twoor three 8511/8611 (or better) in each wing. If using JR/Graupner 8411‘s you must install 3servos per aileron. Futaba users should install 3 servos for each aileron - either 3 of the larger S9152’s, or 3 of the standard sized S9351’s.

2. Aluminium servo arms (6-8 pieces) for ailerons and elevators, and Aluminium servo output discs for the rudder servos (3 pieces). It is mandatory to attach the included phenolic servo extension arms for all 3 rudder servos to metal servo output discs (eg:‘Hangar 9’#HAN3520), or use full metal servo arms (eg: SWB ‘Double-Loc’ type)

3. Throttle servo. Any standard servo will do (eg: JR/Graupner 4041/5391)

4. Aluminum Spinner 125 - 150 mm/5 - 6” dia. eg: Tru-Turn.

5. Main wheels 125 mm ( 5"). Kavan Light or Dubro wheels are recommended.

6. Engine 150cc. The DA-150 is probably the most commonly used engine for our 3m span planes, and the mounting dimensions are shown for this motor. another option would be the 3W 157cc twin, which also fits completely in the cowl and is even more compact than the DA-150.

7. Muffler/Canisters, and headers (80 - 90mm drop). A complete set for the DA-150, including headers, teflon connectors, spring clamps and MTW TD110 canisters is available from us as an option. (Product #910150)

8. Tailwheel assembly. (Available as an option from C-ARF. Product # 801001.)

9. High quality heavy-duty servo extension cables, with gold connectors. High qualityreceiver and ignition switches, etc.

10. Receiver and Ignition batteries.

11. Powerbox and powerswitches for dual batteries (available from C-ARF as an option)

12. Fuel tank (1200 - 1500cc/50 fl.oz) with gasoline stopper. We used a Dubro #692.

13. Cable ties in various lengths.

14. Propeller. Carbon Meijzlik or Menz 32 x 10 or 30 x 12 for DA-150.


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ToolsThis is a very quick and easy plane to build, not requiring difficult techniques or special equip-ment, but even the building of Composite-ARF aircraft requires some suitable tools! You willprobably have all these tools in your workshop anyway, but if not, they should be available in allgood hobby shops, or hardware stores like "Home Depot" or similar.

1. Sharp knife (X-Acto or similar)

2. Allen key set (metric) 2.5mm, 3mm, 4mm & 5mm.

3. Sharp scissors

4. Pliers (various types)

5. Wrenches (metric)

6. Slotted and Phillips screwdrivers (various sizes)

7. Drills of various sizes

8. Dremel tool (or Proxxon, or similar) with cutting discs, sanding tools and mills.

9. Sandpaper (various grits), or Permagrit sanding tools (high quality).

10. Carpet, bubble wrap or soft cloth to cover your work bench (most important !)

11. Car wax polish (clear)

12. Paper masking tape

13. Denaturised alcohol/acetone, or similar (for cleaning joints before gluing)

Adhesives and Solvents

Not all types of glues are suited to working with composite parts. Here is a selection of what wenormally use, and what we can truly recommend. Please don’t use inferior quality glues - you willend up with an inferior quality plane, that is not so strong or safe.

High performance models require good gluing techniques. We highly recommend that you useeither a slow (minimum 30 minute cure) epoxy resin and milled fibre mixture, or a slow filledthixotropic epoxy for gluing highly stressed joints (eg: Hysol 9462). The self-mixing nozzles makeit easy to apply exactly the required amount, in exactly the right place, and it will not run or flowonto places where you don’t want it! It takes about 1 - 2 hours to start to harden so it also givesplenty of time for accurate assembly. Finally it gives a superb bond on all fibreglass and woodsurfaces. Of course there are many similar glues available, and you can use your favourite type.

1. CA glue ‘Thin’ and ‘Thick’ types. We recommend ZAP, as this is very high quality.2. ZAP-O or Plasti-ZAP, odourless, or ZAP canopy glue 560 (for clear canopy)3. 30 minute epoxy (stressed joints must be glued with at least 30 min & NOT 5 min epoxy).4. Loctite Hysol 9462 or equivalent (optional,, but highly recommended, for stressed joints)5. Epoxy laminating resin (12 - 24 hr cure) with hardener.6. Milled glass fibre, for adding to slow epoxy for stronger joints.7. Micro-balloons, for adding to slow epoxy for lightweight filling.8. Thread-locking compound (Loctite 243, ZAP Z-42, or equivalent)

We take great care during production and Quality Control at the factory to ensure that all jointsare properly glued, but of course it is wise to check these yourself and re-glue any that might just


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have been missed.

When sanding areas on the inside of the composite sand-wich parts to prepare the surface for gluing something ontoit, do NOT sand through the layer of lightweight glassclothon the inside foam sandwich. It is only necessary to roughup the surface, with 80/120 grit, and wipe off any dust withacetone or de-natured alcohol (or similar) before gluing tomake a perfect joint. Of course, you should always prepareboth parts to be joined before gluing for the highest qualityjoints. Don’t use Acetone for cleaning external, painted,surfaces as you will damage the paint.

Tip: For cleaning small (uncured) glue spots or marks off thepainted surfaces you can use old-fashioned liquid cigarette-lighter fuel, like ‘Ronsonol’ or equivalent. This does not dam-age the paint, as Acetone and many other solvents will, andthis is what we use at the factory.

At Composite-ARF we try our best to offer you a high quality kit, with outstanding value-for-money, and as complete as possible. However, if you feel that some additional or different hard-ware should be included, please feel free to let us know.

Email us: [email protected].

We know that even good things can be made better !

Did you read the hints and warnings above and the instructions carefully?

Did you understand everything in this manual completely?

Then, and only then, let’s start assembling your Composite-ARF Yak 3m


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TIP: Lighter fluid is excellent forcleaning small marks, clear wax,uncured glue, or similar off thepainted surface of the plane -without damaging the paint.

Building Instructions

General Tips:We recommend that you follow the order of construction shown in this manual for the fuselage,as it makes access to everything easier and saves time in the end. The wings and stabs can bedone at almost any point, and only need servos installing anyway.

The first thing to do is protect the finished paint on the outside of the model from scratches anddents during building - so cover your work table with a piece of soft carpet, cloth or bubble-plas-tic. The best way to stop small spots of glue getting stuck to the outside of the fuselage is to givethe whole model 2 good coats of clear car wax first, but of course you must be sure to removethis 100% completely before adding any decals or markings. Additionally you can cover themajority of the fuselage with the bubble-plastic used to pack your model for shipping, fixed withpaper masking tape, which also protects it very well.

When sanding any areas of the inside of the fuselage to prepare the surface for gluing some-thing onto it, do NOT sand right through the layer of glasscloth on the inside foam sandwich !It is only necessary to rough up the surface, with 60/80 grit or equivalent, and wipe off any dustwith alcohol (or similar) before gluing to make a perfect joint.

Before starting construction it is a good idea to check inside the fuselage for any loose glassfibres that could cut your hands, and a quick scuff over any of these with a coarse Scotchbritepad will remove them.

Note: It is very important to prepare the inside of the fuselage properly, by roughing up andcleaning the surface, before gluing any parts to it.

Landing Gear

The 1st job is to fit the landing gear legs, andyou can leave these in place if you wish toprotect the bottom of the fuselage duringassembly and gear installation.

The Composite-ARF landing gear for the Yaksconsists of 45 deg laminated carbon fibre andfibreglass cloth and a huge number of rovingsinside, all made under vacuum and heat-cured. However it is still light weight, andretains enough flexibility to take the shock outof any imperfect landings.

The legs are fitted through the glassfibre sleeves that are installed at the factory, and bolted tothe composite plywood bulk-heads and plates as shown here with the M6 x 20mm bolts andlarge washers. The spacer blocks on the underside of the plywood mounting plate are factory-installed.

The carbon legs should be quite a tight fit in the fibreglass sleeves, but if they are too tight youmay need to scrape the joining seam with a sharp knife for a smooth fit. Both main legs are iden-tical, and can be used either side.


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(above) The main parts used to assemble theLanding Gear.


Fit the wheelpants to the legs as follows: Setthe fuselage on a level surface with the tail-wheel (optional tailwheel assembly availablefrom C-ARF) in place.

Drill a 6mm Ø hole centrally right thru’ therounded part of the wheelpant. Fit the wheel-pants over the M6 x 70mm axle bolts, andalso temporarily fit the wheels, and screw thebolts into the threaded inserts that are mould-ed into the legs during manufacture.

Looking from the side view, adjust the angle ofthe wheel pants so that the tops of both are parallel witheach other, and the bottom edges angle upwards a little, asshown in the photo below. When satisfied with the angle,temporarily tack the wheelpants to the carbon landing gearlegs with a small drop of thin CA. Remove the wheels andaxle bolts very carefully, and then secure the wheelpants tothe legs with 2 small sheet-metal screws (2.2 x 10mm), into1.8mm Ø holes drilled into the ends of the carbon legs.

You can use any 5" main wheels of your choice. Kavanwheels are very lightweight, but not very durable on asphaltrunways, and Dubro wheels are a little heavier but muchmore solid, and this is what we use at C-ARF.

The order of the items on the axle bolt is: Bolthead, wash-er, wheel hub, 2 or 3 washers, M6 nut (with Loctite), wash-er, fibreglass wheelpant, carbon landing gear leg. You mayneed to adjust the number of washers, or even add a 6mmwheel collar behind the wheel to maintain free wheel move-ment and centre the wheel against the wheelpant, depend-ing on the actual wheels used. A drop of loctite on the M6axle bolt where it goes into the threaded insert in the leg isgood insurance.

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(above) The carbon legs aresecured using the M6 x 20mm boltsand large washers. (below) Wheel axles are M6 x70mm bolts, which fit into thethreaded inserts in the mouldedcarbon legs. The supplied washersare used as spacers, with a plainnut against the outer plywood faceof the wheelpant.

(left/below) Completed wheelpantwith 5” Dubro wheels. The angle ofthe wheelpants to the legs is setwith 2 small sheetmetal screws,thru’ the wheelpant into the car-bon leg.

TailwheelThe tail wheel unit shown is an optionalpart available from C-ARF (# 801001),and is mounted with 4 sheet metalscrews and 4 plastic ‘U’ brackets underthe fuselage, screwed into the plywoodreinforcement that’s installed in the fuse-lage at the factory.

You don’t need to make the tailwheelsteerable if flying from grass surfaces; asimple castoring action is fine.

However, for hard runways you may prefer to connect it either to the rudder horn with 2 smallsprings, or a thin ‘V-shaped’ piano wire into a tube glued to the bottom edge of the rudder, asseen here. ‘Z-bends’ secure the wires into the tailwheel tiller arm. Because of the geometry ofthe Yak fin and rudder, the method shown above is a highly recommended solution for operat-ing the steerable tailwheel, and gives accurate steering.Remember - keep it lightweight at the tail end!

Cowling and Air Vents

The 1 piece cowling is already cut andtrimmed at the factory for you. Secure it to thefuselage with 8 equally spaced (approx.153mm centres) M3 x 12mm bolts, washersand T-nuts (fitted inverted) that are gluedinside the fuselage (photo right).

Tape the cowl into position, and drill the Ø3mm holes 7mm from the back edge of thecowl, inserting a bolt in each after you havedrilled it to maintain perfect alignment.Remove all bolts and add a drop of light oil, orwax, to the threads. Sand the inside of thesurface in the positions that the T-nuts will besecured.

Reinstall the bolts, and screw on the T-nutswith the spikes facing inwards, reaching thru’the front of the cowling. Secure each T-nutwith one drop of thick CA, then remove thebolts, and fix the T-nuts properly with some 30minute epoxy and micro-balloon mixture.Mark the top of the cowling (on the inside) soyou always fit it in the correct orientation.

The Yak has 8 cnc pressed and punched alu-minum air vents included in the kit, alreadypainted to match your fuselage. The cutouts inthe fuselage for the lower 4 vents are factory-


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(above) Cowl is secured to fuselage with eightM3 bolts and T-nuts, glued to the inside of thefuselage with the spikes facing inwards.(below) The 8 punched aluminum louvres aresecured to the cowl with the small sheetmetalscrews, into small ply blocks glued on the insideof the cowl with thick CA.

cut for you, and the upper 4 vents should nothave cutouts - in effect they are just ‘dummy’vents. This is so that all the air coming inthrough the front of the cowl must go thru’ theengine cylinder fins and out of the lower ventsfor the most efficient cooling effect.

The air vents should all be equally spaced40mm apart, with the front edge of the metalvent 55mm from the step in the molded flangeon the front of the fuselage (see photo).

These vents are all fixed to the fuselage usingthe small 2.2 x 10mm sheetmetal screwsincluded in the hardware pack, which gothrough the fuselage skin into small (10 x12mm) plywood blocks cut from the 12mmwide ply strips included. Sand the area incarefully and glued the blocks to the inside ofthe fuselage with thick CA, at the corner ofeach air vent.

Canopy Frame

The fibreglass canopy frame mountings arealready completed for you at the factory. It issecured to the fuselage with four M4 x 12mmallen bolts, fitted from the outside of the fuse-lage, through the plywood tongues that areglued to the canopy frame, into M4 T-nuts.This system has been very well proven on allof our aerobatic planes, and is a strong andrigid solution.

Fitting the clear canopy into the frame can bea little bit tricky, and this is a step by stepguide of how we do it. Of course you can alsouse own your favourite glue and method.

Sand the inside edges of the canopy framecarefully with 120 grit sandpaper, especiallythe fibreglass joining tapes, to ensure a per-fect fit of the canopy. Fit the canopy frame onthe fuselage and secure with all 4 bolts.Roughly cut the canopy molding to shape,and lay it on top of the frame, view from thefront to check that it is centred and symettri-cally positioned, and then mark the approx.shape with a felt pen or wax crayon. There isan approx. ‘cut-line’ molded into in the edgesof the canopy to assist you, and you shouldstart by trimming 4 - 6mm outside this line.


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(above) The fibreglass canopy frame has the 4fixing tongues, the 2 alignment tabs and the boltfixings all factory-finished for you.(below) Detail of the factory-finished canopysecuring tongues, which are secured with M4 x12mm bolts & T-nuts

(above) Only the lower 4 louvres have cutouts,the top 4 louvres are just ‘dummy’ air vents, andshould not be cut out.


Unless you are in a very warm room, we rec-ommend that the canopy is slightly warmedup with a hair dryer to prevent cracking, but becareful not to melt or deform it! When thecanopy fits inside the frame, tape it into posi-tion temporarily, and accurately mark the edgeof the frame on the canopy with a wax crayon.Remove the canopy and trim exactly toshape, leaving about 6mm overlap outside theline all around.

Tape the clear canopy into position on theinside of the frame, and refit the frame to thefuselage and bolt into position. Make visualcheck from the front and back to make suresure that the canopy is straight. Make severalhandles with strong tape, as shown, to makeholding and positioning the canopy easier.

Using the tape ‘handles’, pull the canopy uptightly inside the back of the frame and fix thebottom 2 back corners with one very small drop of odorless CA each (ZAP-O recommended).Check again that the canopy is straight, viewing from the back and front.

Using the tape handles to pull the canopy outwards firmly against the frame, working from theback towards the front, glue the edges of the canopy in place in 2 more places each side, withjust a single small drop of odorless CA at each position, all the time checking that the edge ofthe canopy is tight up against the frame at the front.

Note: Do NOT use any CA accelerator/kicker - you will immediately ‘fog’ the clear canopy!

Now that the canopy is fixed in position and cannot twist or warp anymore, you can carefullyremove the canopy frame from the fuselage, and use a specialised canopy glue (eg: ZAPFormula 560) or slow epoxy and micro-balloons mixture for gluing all the edges to the frame onthe inside surface (see photo above). It is most important that the canopy cannot come off inflight, so make sure that the bead of glue traps the clear canopy firmly in place. Re-secure thecanopy frame onto the fuselage with all 4 bolts while the epoxy-microballoons mixture is curingto prevent any warps or twists.

If you want a completely rattle-free canopy, you can fill any slight gaps at the front and back ofthe frame with a bead of clear silicone. Apply shiny brown plastic tape to the front and backedges of the opening in the fuselage and wax twice with clear car wax. Sand lightly, and de-grease edges of canopy frame where the silicone will be applied. Apply a small bead of clear sil-icone to the front end of the frame only, and secure the frame into position with all 4 bolts untilcured. Remove frame, and trim off excess silicone with a very sharp knife. Then repeat for theback edge. Do not try to do the back and front at the same time - or you will find it very difficultto get the canopy frame off the fuselage!

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(below) Duct-tape handles used to pull theclear canopy against the canopy frame while glu-ing it in position with a few small drops of odor-less-CA. Remove canopy and secure the edgesof the clear canopy with a bead of epoxy to trapit in place (see photo above)


Horizontal Stabs

The stabilisers are finished at the factory, andonly need the servos and linkages installing.Insert the Ø 20 x 435mm long aluminium tubespar in the fuselage sleeve, and slide on bothstabs. The 10mm carbon anti-rotation dowelsfit into the carbon tube in the fuselage and thealignment and incidence has already been setin a jig at the factory for you. The stabs areretained on the aluminum tube with an M3 x16mm allen bolt thru’ the bottom surface ofeach stab, and these are already factory-finished.

The elevators are hinged to each stab usingthe Ø 4mm aluminum tubes provided. Makesure there is no burr on either end of thetubes, and chamfer one end slightly with finesandpaper to make it easier to get themthrough the holes in the phenolic hinge plates.Be careful inserting them, and if they are a bitstiff, then use a little grease on the tubes.Don’t use too much force, otherwise a pheno-lic hinge post inside might break loose. Leavethe tubes a bit too long during assembly, andcut them to exact length when the model is fin-ished. We supply the hinge tubes with quite atight fit in the phenolic hinge posts - but afterthe first 2 or 3 flights they will free up com-pletely and give smooth movement.

During final assembly, secure the inboardends of the hinge tubes with small pieces ofclear tape on the root end of the elevatorsbefore flight.

ServosThe elevators are designed specifically to becontrolled by a single very high torque digitalservo in each stab, and we strongly recom-mend that you only use a JR8711 or JR8811servo. Do not substitute a servo with lowertorque, such as a 8511 or 8611, as it might notbe sufficiently strong enough to prevent flutter.

If using Futaba servos, we recommend thatyou use S9152’s (or better), but you will needto open up the milled cutouts in the plywood ribs as these are a bit wider than the 8711 or 8811servos. The Futaba S9351 is not strong enough to be used in the stabs. The servos should beinstalled with the output shafts nearest to the trailing edge of the stabs.

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(below) Milled 3mm thick plywood doublers areincluded for both the JR8711/8811 and theFutaba S9152 servos. JR8811 and SWB 1.5” servoarm shown here.

(above) Elevator horns, spar tubes, stab secur-ing bolts, anti-rotation dowels and servo armslots are all factory-finished.(below) A single JR8711 or 8811 servo isinstalled in the milled mount in the ply rib, andconnected using a 1.5” SWB metal servo arm,and the linkage hardware supplied.

The 3mm thick plywood inner rib in the stabsis already milled with a cutout to suit theJR8711/881 servo, but it is mandatory thatthe very powerful stab servos are screwedinto 6mm thick plywood, using the Ø 2.9x167mm long screws provided. For this pur-pose we have included 3mm plywood dou-blers (2 to suit JR8711/8811 and 2 for FutabaS9152), which must be glued securely to theinside face of the plywood rib. If fitting the JRservo all you need to is glue one 3mm doublerinto each stab with thick CA, aligning thescrew fixing holes carefully with some pins,and then cut out the temporary ‘spacer’ bar inthe middle when the glue has cured.

If you are fitting the S9152 servo then, aftergluing the doubler into place and cutting outthe spacer bar, you will need to enlarge theoriginal milled cutout in the rib a little to suitthe slightly larger Futaba servo. A coarsePermagrit needle file, with an extension han-dle, makes this a quick job.

Servo armsIt is mandatory to use full metal servo arms for the eleva-tor control, and we always use the SWB 1.5” double-locarms (shown here) which provide full deflection throwswithout having to electronically reduce the end-points, toensure the highest torque and mechanical advantage.These arms clamp onto the servo output shaft with no lostmovement (play) at all. They are high quality, properly engi-neered arms, and are available from many good hobbystores.

If using the SWB arms you may need to reduce the thick-ness of them a little at the end so that the supplied alumini-um clevises fit without binding, and this is easily done on abelt sander. Drill the outer hole to 3mm diameter for the cle-vise pin, and apply a little grease to the hole to make surethere can be no binding of the Ø 3mm pin in the servo arm.

Whatever brand of metal servo arms you use, make sure that they are a tight fit on the splinesof the servo output shaft, with no slop or lost movement at all - otherwise you increase the riskof flutter!

Centre both your servos using the R/C, and secure the metal servo arms tightly before installingthem into the stabs. Add a drop of Loctite to the bolt that secures the arms to the servos.

Make up the linkages as shown, using the M3 x 70mm threaded rod supplied, with the aluminumclevise and a plain nut at the servo end, and the M3 ball-link at the elevator end. Make sure thatthe threaded rod is screwed fully into the shank of the plastic ball-link. The ball-link is secured


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(above) Servo is screwed into the milled cutoutin the inner rib, which must have the includedplywood doubler glued to the inside face togive a total 6mm thickness.(below) JR8811 servo & SWB 1.5” servo arm.

(above) You may need to sand theends of the SWB arms a little forsmooth movement of the clevises.Remember to add a little grease tothe clevise pins.

between the dual phenolic elevator horns using the M3 x20mm allen bolts and lock-nuts provided in the hardwarepack. Add a drop of Loctite for extra safety.

It is allowed to fit a single-sided ball-link onto the metalservo arms to adjust the line of the linkage if necessary -but you must not fit a ball-link to a single-sided phenolic orplastic servo arm.

Static balanceBecause the Yak elevators have very large counterbal-ances, it does help to reduce loads on the servos if you add15 - 20 grams of lead into each one, inserted through asmall hole drilled as shown, and epoxies into place.

ThrowsIf you need more travel on the elevators than the factoryassembly allows (about 40°) you will need to increase thelength of the slots in the composite/balsa ‘false’ leadingedge of the elevators with a small file. The outer 2 slots inparticular will need to be longer, and you can extend themalmost right out to the composite skin. Unfortunately it’s notpossible for us to mill these slots longer during manufacture- as the L.E. spar would fall apart on the CNC milling table.However, this is a very quick job with a Permagrit file, orsimilar (see photos right), and you can easily achieve 50degree throws if you wish.

RudderThe rudder is completely finished at the facto-ry, with the dual phenolic rudder horns gluedin, and the phenolic hinge posts aligned andsecured - ready to accept the Ø 4mm brasshinge tube. Fit the brass tube in the same wayas for the elevators, sanding a small chamferon one end to ease insertion - and tape thelower end in place before flight.

Assemble the tray from the milled parts andinstall the servos and phenolic arms outsidethe model, as shown. Lightly sand all compos-ite balsa milled parts first, and glue togetherwith thin CA. Add the 3mm thick plywoodstrips underneath each servo rail, cut from the12mm wide ply strips provided. Then reinforceall joints with 30 minute epoxy. The length andangles at both front and back can be sanded,if necessary, to fit exactly between the back ofthe muffler compartment and the bulkhead atthe back of the cockpit opening (see photobelow).


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(above) Insert 15-20 grams of leadthru’ a hole into the front of thecounter-balance of each elevator.(below) You can increase availablethrows by lengthening the slots inthe leading edge of the elevators,especially the 2 outer slots.

(above/below) Assemble the rudder tray withthin CA, as shown, with the plywood strips gluedunderneath with epoxy.

Servo ChoiceThe milled composite rudder tray is designedfor 3 JR servos (8511/8611) or better. If usingFutaba you can also fit the large S9152 ser-vos, although you will need to sand about2mm from the edges of the servo rails.

Fit the 3 rudder servos into the tray, with theoutput shafts nearest to the tailplane, andscrew into position using the 2.9mm Ø x13mm long sheet-metal screws supplied.

Servo armsThe supplied phenolic rudder servo outputarms must be bolted to 1” or 1.25” diametermetal servo output discs. We used ‘Hangar 9’# 3520’s. Please do not use the standardplastic discs for this, as there is a chance thatthe internal plastic splines can be stripped bythe current hi-torque servos - causing instantrudder flutter, and probable loss of your plane.

Fit 3 metal output discs to the servos, andrough sand the top surfaces of the metal discsand the underside of the phenolic arms.Centre the servos with your R/C, and thenglue the phenolic arms onto the discs withepoxy, aligning them carefully so that they areexactly parallel and at 90 degrees to the sidesof the tray in the neutral position. Make surethat the slots are facing forward on the rearphenolic arm.

When the glue has cured drill thru’ the armsand discs and secure with 2 of the M2 boltsand nuts on the front 2 servos, and 3 bolts forthe rear arm.

Make up the linkages from the hardware sup-plied, joining the servos together as shownwith the threaded rods, ball-links and steelclevises. Enlarge the holes in the phenolicarms to Ø 3mm where the ball-links aresecured with the M3 x 16mm bolts and stop-nuts. Fit just one of the linkages between thephenolic arms at a time, and adjust the lengthof the linkage very carefully until so that thereis minimal buzzing or humming from the ser-vos at idle, and at full throw. When satisfied,add the next linkage and follow the samemethod of adjustment.


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(above) Centre the servos with the R/C, and boltthe metal discs to the servos. Rough sand topsurface before gluing on the phenolic arms.(below) You must bolt the phenolic arms tometal servo output discs, using the M2 bolts andnuts provided.

(above) Completed rudder servo tray.(below) Sand small rounded dimples about0.5mm deep for proper clearance of the M3steel clevises, only on one side of each pheno-lic horn, as shown here.

Due to the manufacturing tolerancesof the phenolic material you may findthat you need to sand small dimples inthe top surface (only) of the phenolicarms where the steel clevises are fit-ted, to make sure that they close com-pletely and have free movement. Adrum sander with a rounded end (eg:Permagrit) in a Dremel or similar,makes this a quick task. The dimplesonly need to be about 0.5mm deep.See photo above.

The servo mounting tray should beglued securely to the bottom of thefuselage between the angled backface of the muffler tunnel and the ringbulkhead at the back of the cockpit.Sand the ends of the tray if necessaryfor a perfect fit, sand the inside of thefuselage, and then glue in securelywith slow epoxy and micro-balloonsmixture, or Hysol.

The pull-pull cables that connect therear arm to the rudder horn should becrossed, so that they exit under thestabs. The slots that you need to cutfor the pull-pull cables to the rudder are 230mm (9 1/8”) forward of the back edge of vertical fin(immediately in front of the rear bulkhead) and 70mm from the bottom seam of the fuselage. Cutout a small slot first with a very sharp knife, check the position using the pull-pull wire, and thenadjust and open up the slots with a small file as needed. The slots should be about 3mm highand 35mm long.

Make the pull-pull wires from the hardware supplied, with a loop at the front that goes over thehooks on the output arms, and a quick-link with threaded extender (turnbuckle) and locknut atthe rudder end. The ball-link is bolted in between the dual rudder horns with the M3 x 20mm boltsand stop-nuts.

Pass the closed loop cable through the supplied ‘crimping tubes’ 2 times before squashing flatwith pliers. Make sure that the wires are tight, and check and adjust after the first few flights asthe cables straighten out. Even a small amount of slop will prevent your Yak from perfect track-ing. You can glue a very small scrap of ply or balsa across the front of the slots on the servo armswith a drop of CA to prevent the wires coming out of the slots accidentally, for example when therudder is removed for transport.

You can increase the lengths of the slots in the rudder L.E. in same way as for the elevators toachieve extra throw if necessary.


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(above) Rudder servo tray glued into the fuselagebetween muffler compartment & rear cockpit bulkhead.(below) The slots for the cables are immediately in frontof the rear bulkhead, 230mm from the back of the fin.

Wings

The wings are 95% finished at the factory, andhave already been installed on your fuselageto set the alignment. Dual phenolic aileronhorns are already pre-installed for you at thefactory. Slide the wings onto the 50mm diam-eter alloy wing tube, and fit the 4 plastic wingretaining nuts onto the M6 threaded alumini-um wing dowels. Each aileron has 2 or 3 ser-vos (depending on your servo choice) fittedinto cnc milled phenolic mounting plates thatare screwed into the cutouts in the inner andouter plywood ribs. For easier access wehave included a milled servo hatch to fit in therecess over the outer servo position, and youwill need to mill the slot in it to suit the exactposition of your chosen servo arm.

Wing TubeThe wing tube is a 50mm Ø T6 alloy, whichslides inside a fibreglass sleeve in each wing,and it should be 1035mm (38.5”) long. Pleasecheck the length to make sure that it passesthrough the inner plywood ribs in each wing,that are about 355mm (14”) from the root, oth-erwise the wing could fail in flight.

Servo ChoiceIf you chose to use only 2 servos for eachaileron then one of these must be installed inthe rear position of the inner phenolic mount,and the other in the outer phenolicmount. Any slight mis-match of the ser-vos will not cause servo damage dam-age due to the slight torsional flexibili-ty of the large ailerons.

If fitting 3 servos for each aileron, thenthe inner pair are ganged together asshown in the photos here. Fitting 3powerful servos to each aileron doesmake the snaps a little ‘crisper’, and ifyou chose lower power digitals, likethe JR8411 or Futaba S9152/S9351then you must install 3 servos perwing.

JR/Graupner: 2 x 8511/8611’s arequite sufficient for each aileron, asused in the prototype. Even better is apair of 8711/8811 servos - one


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(above) Each aileron is controlled by two orthree servos installed in phenolic mounts thatare screwed to the plywood ribs in the wing. (2x JR 8511 servo set-up shown here)(below) Included in the kit are phenolic servomounting plates for both JR and Futaba servos.

(below) Phenolic servo mounts and 3 x JR 8511servos installed in the milled cutourts in the winginternal structure.

installed at the back of the inner phe-nolic mount and the other in the outermount. For the ultimate response fitthree x JR 8511/8611 or 8711/8811servos.

Futaba: We strongly recommend thatyou only install 3 servos, not 2. Either3 x S9351’s or 3 of the larger S9152’s,and special phenolic mounting platesare included for these.

Servo MountingSecure the servos to the phenolicplates (without using the rubber grom-mets and brass ferrules) as shown,using the supplied M3 x 12mm allenbolts, washers and M3 lock-nuts.Align the servo cases exactly parallelto each other using a steel ruler on theservo case sides.

The inner servos should be installedwith the output shafts towards theleading edge of the wing, and the outerservo is installed with the output shaftclosest to the trailing edge.

The phenolic plates are isolated fromthe ribs using the grommets and brassferrules originally supplied for fittinginto the servos, as shown here. Fitthem into the milled semi-circularcutouts around the edges of the phe-nolic mounts. You will need a couple ofextra grommets and ferrules for this.

Servo ArmsIt is mandatory to use full metal servoarms for the aileron controls, and wealways use the SWB double-loc arms(shown here).These arms clamp ontothe servo output shaft with no lost movement (play) at all. We used 1.5” arms on the rear twoservos, and a single 1” arm on the front inner ‘ganged’ servo.

Whichever make of metal arms you use, chose the lengths carefully to provide full deflectionthrows without having to electronically reduce the end-points, to ensure the highest torque andmechanical advantage.

If using the SWB arms you will need to reduce the thickness of the 1.5” arms a little at the endso that the supplied aluminium clevises fit without binding, and this is easily done on a beltsander (see photo on page 16). The 1” SWB arms used for the front (ganged) inner servo are


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(above) Dual inner aileron servos installed in the pheno-lic mounts provided, ‘ganged’ together with metal servoservo arms using the hardware provided in the kit.(below) The single outer servo installed in the phenolicmount, and screwed to the plywood rib.

(below) Back view of the inner ganged servos, showingthe lock-nuts that secure the servos , and the grommetsand brass ferrules fitted around the perimeter of themounting plate. Note that the 1.5” SWB arm has beensanded a little for a good fit of the clevise.

already the correct thickness for the M3 alu-minum clevises provided. Drill out the thread-ed holes in the SWB arms to 3.0mm diameterfor the clevise pins, and apply a little grease tothe hole to make sure there can be no bindingof the Ø 3mm pin in the servo arm.

Secure your chosen metal servo arms to theservos, centering them all with your R/C sothat the arms will be at 90 degrees to the bot-tom wing surface (not to the servo case).Connect the outer hole on the front innerservo arm (if used) to the 2nd hole from thecentre on the rear 1.5” arm as shown, andadjust the linkages between the 2 inner ser-vos carefully to eliminate any buzzing, or fight-ing between them.

Install the completed outer servo mounts intothe wing first, screwing them to the plywoodrib using 6 of the Ø 2.9 x 13mm sheetmetalscrews provided in the hardware pack, asshown. The rib has small ply doublers factory-installed on the outer face of it. It does makethe outer servo fixing easier if you make up avery long x-head screwdriver so that you canaccess the screws from the wing root. Installthe inner mount in the same manner, using 10screws.

If using dual ‘ganged’ servos in the inner phe-nolic mount you will need to lengthen thesmall servo arm slots that we have alreadymade in the bottom wing skin.

Check that the servo output arms are aligned with the dual phenolic aileron horns, and correctany misalignment by adding thin plywood shims under the phenolic mounts if necessary.

Mill a slot in the servo hatch covers for the outer servos, to suit your servo arm, and secure inposition using the Ø 2.9 x 10mm screws provided. The small slots in the wing underside for theinner servos will need to be made larger - to suit the exact location of your servo arm.

Make up the linkages as shown, using the M3 x 90mm threaded rod supplied, with the aluminumclevise and a plain nut at the servo end, and the M3 ball-link at the aileron end. Ensure that thethreaded rod is screwed fully into the shank of the plastic ball-link. The ball-link is securedbetween the dual phenolic aileron horns using the M3 x 20mm allen bolts and lock-nuts provid-ed in the hardware pack. Add a drop of Loctite for extra safety.


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(above) Inner servo linkage shown using a singleservo, installed in the rear of the phenolicmount. If using dual ‘ganged’ servos you willneed to extend the servo arm slot forwards forclearance on the front servo arm. (below) Aileron linkages are assembled usingthe provided hardware. Outer servo hatch issecured with Ø 2.9 x 10mm screws. Mill the slotsin the hatches to suit your metal servo arms.

Engine Installation

We strongly advise you to complete the motorand exhaust installation before the fuel tankbase and the vertical former at the back of thelanding gear mount plate are installed, as it pro-vides much easier access.

Here we show a DA-150 motor installed, with apair of MTW TD110 canisters, and this is anexcellent combination. Another suitable motorwould be the 3W 157cc X1 B2 twin, which ispowerful and very compact - and easily fitsinside the 376mm diameter (14.8”) cowling.

The front surface of the motor-dome and firewallalready has approx. 1.5 degrees of sidethrustbuilt into it, and the downthrust is nominally setat 0 degrees. However, due to manufacturingand assembly tolerances these may vary slight-ly, and you can check the precise angles of thefirewall in your plane with an inci-dence meter.

Accurately mark the exact verticaland horizontal centrelines on the ply-wood firewall. Cover it with maskingtape and measure from the insidesurface of the circular fuselage, ver-tically and horizontally. You shouldfind that the centre will be 188mmfrom the inner surfaces.

The Composite-ARF Yak only needs1 - 1.5 degrees right thrust, so themotor only needs to be offset to the(pilots) left by 5mm to have the cor-rect thrustline and the spinner centrally posi-tioned. Mark another vertical line 5mm to the(pilots) left of the fuselage centerline as shown.

The downthrust required is also very small atapprox. 0.5 degrees, so you should offset thecentre of the motor about 1 - 2mm above thehorizontal centreline. Both the DA-150 and 3W157 Xi require standoffs of 25mm (1”), and theremaining small adjustments for final thrustlinesettings are made by adding the included largediameter washers between the firewall and thestandoffs.

The mounting plate for the DA-150 has horizon-


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(above) Centrelines and offsets marked on thefirewall to suit DA-150 mounting. (below) The DA-150 is fitted on 25mm longstand-offs, and the final side & down thrust setusing washers between them and the firewall.You can also seen the ignition unit, secured bycable ties onto the top of the motor dome.

(below) Another DA-150 view showing theheaders and the location of the hole thru’ thefirewall for the Tygon fuel tube.

tal hole centres of 80mm and vertical centres of90mm, so mark these offsets either side of themotor centreline as shown. Drill the 4 fixingholes Ø 6mm, and secure the motor to the fire-wall using the M6 x 55mm bolts, and the T-nutsagainst the inside face of the firewall. Addwashers as needed behind the standoffs to setthe correct thrustline, and then fit your spinnerbackplate to check that it will be centrally posi-tioned in front of the cowling.

Don’t forget to add a drop of Loctite to all theengine mounting bolts during final assembly.

Fuel-proofingWe highly recommend that you fuel-proof theplywood firewall, and all bare wood inside themotordome/tank base area with a thin coat oflaminating resin, to protect your investment inthe case of a fuel leak. It’s wise to do this now,before the motor is finally installed.

Canister and Header InstallationIncluded in the wood pack is a milled plywoodbulkhead designed to suit the excellent MTWTD110 mufflers (or similar Ø70 cans), and thismust be glued into the muffler compartmentapprox. 440mm (17.5”) back from the front ofthe fuselage. No other support is needed.

Cut eight 20mm lengths of the hard siliconetube provided, and insert into the milled slots inthe corners to make the isolation mounts (seephotos on next page).

Sand the outside edges of the plywood supporta little to fit (if necessary) so that it does notdeform the fuselage of muffler compartment,sand the gluing areas very well, clean off thedust and tack-glue in glue in position with a fewdrops of thick CA. Now trial fit your headers andthe 70mm canisters to your motor and carefullypush them into the muffler support to check thatthe position is correct.

Check that there is at least 8mm (3/8”) betweenthe canisters and the fuselage/muffler compart-ment/landing gear support tubes in all positionsso that there can be no heat damage, and ifnecessary bend the headers a little to set thecans exactly in the required position.


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(above) Throttle linkage goes directly back-wards through a slot in the firewall, to theservo which is mounted on the milled plywoodassembly included in the kit.(below) 2 views of the compact 3W 157cc Xiinstalled. The venturi for the carburettor clearsthe fuselage by about 6mm (1/4”)

Exhaust Cooling

Remove the canisters and turn the fuselage over so thatyou can cut out the air exit holes underneath. These shouldbe minimum 150mm long and 45 wide, with radiused cor-ners to prevent the composite sandwich tearing. Leave at50mm space in between the 2 holes, where the carbon join-ing tape is, for strength. If you fly in very warm ambient tem-peratures, extend the length of the slots to 170mm (for-wards to wards the pipe support bulkhead) to ensure suffi-cient air exit flow.

Now you can glue the pipe support bulkhead into the fuse-lage properly, using a slow epoxy and micro-balloons mix-ture, reaching thru’ the air exit holes to glue the rear face.

You will need to make 2 slots of about 25mmwide and 40mm long for the muffler exits,between the landing gear legs as shown.

For security, during final muffler installation,install 2 of the small sheetmetal screwsthough each the teflon joiners into the canisterentries and header ends to make sure that thecans cannot slide forwards or backwards dur-ing flight.

Tuned Pipes.There is more than enough space to fit a pairof tuned pipes in the muffler compartment, butit is too short for full-length pipes. If you wishto fit pipes then you will need to extend theback of the compartment by about 150mm(6”), and reposition the Rudder servo tray ontop of it. However, we have included a pair ofmilled plywood tuned pipe supports in thewood pack, to suit Ø 50mm pipes, such as theGreve units.

In the near future we hope to manufacture amolded muffler compartment extension forcustomers who want to fit full-length tunedpipes.

Motor CoolingIt is imperative that your chosen motor notonly receives sufficient air to cool it throughthe opening in the front of the cowl, but thatthe air is forced to go through the cooling finsof the cylinders - otherwise the air will just takethe easiest route and exit the bottom of thecowl without doing any cooling. In this case


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(above) MTW headers & canistersare available as optional items fromC-ARF. Shown here are the TD110cans and headers for the DA-150.(below) Support bulkhead secure-ly glued into position in the mufflercompartment with epoxy andmicro-balloon mixture.

(above) Make two small 40 x 25mm wide slotsfor the muffler exits.(below) 2 small screws thru’ the Teflon joinersprevent the cans moving in flight.

you will overheat, and damage, your valuable motor.

Depending on your motor you will definitely need to makesome sort of baffle to force the air through the cooling fins,and this can be made from scrap 1.5mm plywood or 3mmbalsa. Cut a half-circle of 330mm diameter and glue it intothe cowling, as shown, and then a horizontal shelf of thesame material which is glued to the back of it and trimmedto clear the cylinder fins by 6mm (1/4”). It looks neater ifyou paint it matt black first, using heat-proof spray paint (asused for car manifolds/exhausts).

Fuel Tank Base

The Fuel tank base supplied is a cnc milled balsa/compos-ite assembly, that also provides space for mounting thereceiver and Powerbus system. It is reversible - so you canassemble it either way around, and fit the Rx and Powerbuson either side of the fuselage.

It is sized to fit a Dubro 1500 cc (50oz) tank (part #692), butcan be adjusted to suit your choice. Depending on the sizeof your fuel tank, glue a scrap balsa block at the front of thetank base to stop the tank moving forwards. Secure the fueltank to the tank base with cable-ties through the milledslots, as shown in the R/C installation section.

Lightly sand all the parts, assemble with thin CA as shown,and then reinforce all joints with a fillet of 30 minute epoxyand micro-balloons. Don’t forget to seal the bare edges ofthe balsa sheet with a brushed-on coat of thin epoxy.

Prepare the areas well for good glue adhesion, and thenpermanently glue the completed tank base in place on topof the fibreglass sleeve for the wing tube, andto the top of the composite side-rails at theedges of the cockpit opening using a slowepoxy and micro-balloon mixture.

The fuel tank is secured to the base using 3cable-ties as shown. The small plywood dou-blers glued underneath the tank base are forthe screws that secure the Powerbox.


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(above) Fuel tank base with 1500cc Dubro #692fuel tank, Power box and Receiver.

(above & below) Top and bottomviews of assembled fuel tank base.

(below) Simple 1.5mm plywoodbaffle to improve motor cooling.

Landing Gear support bulkheadAfter you have completed the fuel tank base, and glued itinto position you must glue in the plywood upper landinggear support bulkhead - which transfers some of the land-

ing loads throughout the fuselage.

This milled part is supplied in the wood pack, and it is notinstalled in the factory to give you better access wheninstalling the motor and R/C gear, batteries etc.

Sand the inside of the fuselage and the top of the LG plat-form carefully and glue this bulkhead in vertically with slowepoxy and microballoons mixture. Do not forget to glue this

bulkhead in before flying your Yak !

R/C & Equipment Installation

Everyone has their own favourite methods,equipment and layouts when fitting the R/Cand gear, and the installation shown here isjust a guide.

We highly recommend a high-quality servopowerbus system and dual Rx batteries forthe ultimate in safety and security, for examplethe Powerbox 40/24 shown. It’s your choice,but the dual Nicad and powerbus installationdoes give extra ‘peace of mind’ and protectsyour investment, and therefore this is what C-ARF recommend and have shown here.

The PowerBox power control unit is designedespecially for large models and provides dualbattery inputs with hi-amp connectors, multi-ple outputs for 7channels/24 outputs (no ‘Y’leads needed), automatic voltage regulationand stability, built-in servo amplifiers for thoselong servo cables, as well as dual visual LEDbattery displays. It comes complete with hi-current connectors and is fitted with anti-sup-pression chokes on all channels. The full‘PowerBox’ range is available from C-ARF asan option. Please visit our website for moredetails.

Ignition BatteriesWe always use 2400 (sub-C sized cells) for


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(above) A general view of the R/C installation,showing fuel tank base, Rx, Powerbox, and dualRX batteries. Ignition battery is located insidethe motordome.

(above) Glue the landing gearupper support bulkhead in posi-tion with epoxy & micro-balloonsafter finally fixing the tank base intoposition.

the ignition system. The 4-cell pack for the DA-150 is secured inside the fuselage against thefront left side of the motor dome with cable-ties on a foam isolation pad.

Receiver BatteriesThe prototype Yak is fitted with two 5 cell NiMH Rx packs of 2400mAH each, and a 4 cell2400mAH ignition pack, and the ready-to-fly weight is just under 18.5 kg (40.5Lbs). If you choseto use LiPo or Duralite packs the flying weight would reduce to about 18 kg.

There is absolutely no problem setting the correct CG on the Yak 3m, and you will see from thephotos that we fitted 1 Rx pack on the tank base, and the other to the back face of the mufflercompartment - both on foam pads and secured with cable-ties. These positions set the ‘pattern’CG without any other weight adjustment.

Make sure that all batteries, and other heavy items, are very securely fixed in the plane - remem-ber how much they will effectively weigh when subjected to 4 or 5 G’s!

ReceiverC-ARF strongly advise that you position the receiver as faraway from the high-voltage ignition unit as possible - atleast 200mm (8”) for the minimum interference risk. Wepositioned the Powerbox Competition and the RX on thebalsa-composite plate on the left side of the tank base.

Please mount the sensitive Receiver on a rubber or foamsheet, at least 3mm thick, to isolate it from vibrations. Youcan easily secure the Rx either using 2 small cable-ties, orby gluing a plywood stick across 2 large holes in the mount-ing plate - using 2 rubber bands around the Rx case. (seephoto above)

RX AntennaThe Rx antenna was routed to the side of the fuselage,then backwards along the fuselage side and out of the topof the fuselage immediately behind the canopy - insertedinto a removable plastic tube. Keep it as far away as possi-ble from the cables for the elevator servos and the closed-loop rudder wires.

SwitchesOften regarded as the ‘weakest-link’ in an R/C system, it isvery important to use quality switches for bothReceiver/Powerbox and motor ignition, and we only usehigh quality switches from Power box. The electronic‘Sensor’ switch included with the Powerbox Competition isa ‘Fail-ON’ type, for additional safety. We use an analog 20Amp power-switch, also from Powerbox, for the ignitionsystem.

If fitting the switches into the outside surface of the fuselage, as shown, you should reinforce thearea inside with a small patch of 3mm thick plywood to reduce vibrations transmitted to theswitches. It only adds a few grams. The Powerbox switches come with paper templates, makingit easy to cut the slots in the fuselage accurately.


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(above) PowerBox Switch mount-ed in fuselage side, with ply rein-forcement. Antenna wire and stabextension cables are routed thru’silicone protection sleeves andfixed securely.(below) Protect all wires and tubeswhere they pass thru’ bulkheads,or near sharp composite parts,with a short length of silicone tube,and cable-tie firmly in position.

Servo Extension leads etc.Please make sure that you use good quality twisted-cableextension leads, of heavy gauge wire with gold-contactconnectors, to all the servos. If you are using a ‘Powerbox’this unit is already fitted with all the ceramic chokes. Alsono ‘Y’ leads are needed, as the powerbox provides multipleinputs for each channel.

At C-ARF we hard-wire all our servos with twisted cableleads of the exact length required and Multiplex 6-pin con-nectors (see photo right). For the 2 aileron servos you canuse 1 pin for each wire, and for the elevators you can gen-tly squeeze pairs of adjacent pins together and use a pairof pins for each cable. We glue the female connectors intosmall plywood plates in the sides of the fuselage for con-necting the stabs and ailerons when assembling the plane.Making up the proper extension cables and connectors isonly a little work, if you are proficient with a small soldering-iron, and makes assembly of the model at the airfield veryquick and easy! Once all wires are soldered to the gold-plated pins, fit a short length of heat-shrink tube over eachone. Finally protect all the connections from vibrations etcwith a nice blob of glue from a hot-glue gun. Job done.

Make sure that any plug/socket servo cable connectionsthat cannot be easily seen and regularly checked, forexample the servo connections in the wings, are securedtogether with tape - or a short length of heatshrink tubing asshown here. Also tape down any loose cables that couldget trapped or caught in linkages.

Throttle servoYou can install the throttle servo anywhere you chose,using the milled plywood mount that we supply (photoright). We mounted it inverted, on the underside of the land-ing gear support plate, immediately in front of the left car-bon leg, and this gives a short and straight direct linkage tothe DA-150 carb.

We advise you not to mount it directly on the back of thefirewall, due to higher vibration levels which can quickly ‘kill’the servo. Note that all DA motors need quite a lot of servothrow to get the full throttle range, so make sure you can fita long output arm on the servo.

M3 all-thread, steel clevises and locknuts are included inthe hardware pack to make up your throttle pushrod.

Make up a wire lever so that you can operate the ‘Choke’for starting thru’ the baffle in the front of the cowling.

Motor Ignition SystemThe ignition unit is normally fixed to the motordome, as


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(above) Milled plywood throttleservo mount can be installed any-where you chose. Linkage isincluded in the hardware pack.Assemble with thin CA and thenreinforce the joints with 30 minuteepoxy.(below) Secure the connectionbetween the motor pick-up andthe ignition plug with heatshrinktube of a very small cable-tie.

6-pin MPX connectors are used forextension leads, with one halfmounted in the fuselage sides.

close to the engine as possible - because of the length of the HT leads that connect to the sparkplug(s). Mount it on a foam pad and secure with cable-ties, to the top surface of the motor domeimmediately behind the engine as shown on page 22. Don’t forget that the ignition unit also getswarm during use, so it is wise to put it in a location where there is some cooling airflow. Keep theignition unit as far away from the receiver as possible.

Use a very small cable tie, ‘safety clip’, or a length of heat-shrink tubing to securely connect theplug and socket from the motor pick-up to the ignition unit.

Fuel TankThe fuel tank is held to the tank base with 2 large and 1small able-ties. Drill a hole in the motor firewall as neces-sary for the fuel feed tube from the tank to the carburettor,and protect it where it passes through the hole using a rub-ber grommet or similar.

Fit the correct stopper to the fuel tank for the fuel type used.(If using Dubro tank the gasoline stopper has a small ‘O’moulded in the top of it). We use the excellent ‘Tygon’ brandof fuel tubing for all our aerobatic models. It is totally gaso-line and kerosene-proof, and does not go hard and crackwith age. Secure the feed tube inside the tank to the clunkwith a small cable tie. If the tube is even a little loose on thebrass tubes though the stopper, you can be sure it willcome off at just the wrong moment and your engine will quit ! Therefore please solder some smallrings onto both ends of the brass tubing (easily made from the soft wire of a paperclip wrappedaround a small screwdriver, or short lengths of brass tube) and also secure with a fuel-line clampor cable-tie. Don’t miss this small detail - it could cost you your plane !

We use the normal 3 tube plumbing system, one from the clunk to feed the motor, one out of thebottom of the plane (vent/overflow - leave open) and one at the top for filling (close for flight).

Final CheckNow check that you have fixed all components securely. Keep in mind that all the componentsinside the aircraft are loaded with the same G’s as the wing and the wing spar during aerobaticmaneouvers. Check engine, cowling, wing and stab mounts carefully again.

- Are all extension leads, cables & fuel tubes securely fixed to the side of the fuselage

and cannot come loose when subjected to high ‘G’ forces during flight.

- Are all tubes and wires protected from chafing where they pass thru’ the holes in fibre

glass parts or bulkheads with rubber grommets, or short lengths of split silicone tubing?

- Especially if you have installed the internal mini-pipe set-up, you also must make sure

that no fuel tubing or wires can come into contact the exhausts. Use the plastic spiral-wrap to tidy up groups of cables and make sure that they cannot move around in the plane under high ’G’ manoeuvres by fixing them to the sides with small cable ties. If usingthe easily-available cable-tie plastic fixing plates, please do not trust the double-sided tape that they usually have on them which can fail under vibrations. Peel it off, rough upthe back face with coarse sandpaper and glue to the fuselage sides with 30min. epoxy.

- Did you fit small Tygon or silicone tube pieces over all the clevises?

- Did you tighten the M3 locknuts against all the clevises to make sure they cannot turn?


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(below) Fit barbs to all brass tubesand fuel connections for safety.Easily made from a paper-clip, sol-dered onto the brass tubes.

- Are the swages crimped up nice and tight on the rudder cables?

- For added security add one small drop of loctite/thread locking compound on all the bolts

that hold the servo arms to the servos, especially important with digital types.

Then you can go on set up all the linkages, control throws and R/C system as described below.

Setting Up Your Aircraft

Centre of Gravity: Set the Centre of Gravity to 190 - 200mm(7.5 - 7.9””) forwards from the TRAILINGedge at the wingtip for the 1st flights. Hold itwith a helper at both wing tips in this posi-tion and make sure the plane balances hor-izontally. This is the ‘pattern’ CG position.

Don’t forget to balance the plane laterally,holding the spinner central bolt and a finger-tip under the rudder and, if necessary, adda small weight to the light wing tip to makeit track correctly.

Engine Thrustline: Initially downthrust should initially be set at0.5° degrees and right thrust 1.5 degrees, depending onthe prop used. We recommend a carbon 2-blade 30 x12 ora 32 x 10 on a 150cc motor. It is a very quiet and powerfulsolution. They are normally CNC-designed, so the prop isbalanced perfectly statically, dynamically and aerodynami-cally, which keeps the vibration down to a minimum.

Control Throws:All measurements are at the root/trailing edge position. Allcontrols should be set with a dual rate switch.


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1 - 1.5° right-thrust, and 0.5° down-thrust, depending on propeller

THRUSTLINES

C of G range: 190 - 200 mmfrom Trailing Edge at Wing Tip.

CENTRE of GRAVITY

190-

200m

m

ElevatorOn high rate the elevator should really be atmaximum, up to 50 degrees both sides(approx. 130mm), but in this case with 50%exponential. Low rate should be no more than50mm (2") both sides. This is the perfectthrow for nice and crisp snaps. If you like youcan add about 20% exponential to the lowrate setting as well.

RudderSet the high rate to maximum throw (about170mm) both sides, and at low rate reducedto about 110mm. These throws are measuredat the widest chord of the rudder.

Check your linkages and closed-loop cablesagain and make sure that there is NO slop atall in the rudder set-up!

AileronsAileron throw for high rate is 75 - 80mm upand down (measured at root). Use at least30% exponential at high rate. For low rate youshould decrease the throw to the TOPto 50mm, to the BOTTOM to 55mm.Yes, you’re right - this is a reverseddifferential due to the hinge line beingin the top skin instead of on the cen-tre line. You will have to finalise thisdifferential figure during flight, asmentioned earlier in this instructionbook. At high rate, for 3D maneou-vers, this doesn’t effect the rolling toomuch, so you can maximize thethrows to whatever is mechanicallypossible, even more up than down ifyou wish.

GeneralYour Yak has very large control surfaces. This makes it very sensitive and reactive. It is alwayspossible that these huge control surfaces can flutter at high speeds if the assembly, servo instal-lation and linkages are not made perfectly, and if a servo gear or output disc/arm strips the flut-ter will not stop until the plane hits the ground….

So please do yourself a favour, and make sure that you only use the best servos available, andtake the utmost care making your linkages. Check every linkage for slop, and rather reduce themaximum throw than risking a high speed flutter due to sloppy servo gear or linkages. To pre-vent this for sure, we recommend reduced control travels (reduced by using shorter servo arms,not by using electronic settings). Using 2 servos per aileron as described in this manual willnever overload or damage high quality servos, even if the maximum travel of each servo is slight-


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ELEVATOR THROWS

high rate: 130mm (max.)low rate: 50mm

low rate: 50mmhigh rate: 130mm (max.)

RUDDER THROWS

high rate: 170mm (max.)low rate: 110mm

low rate: 110mmhigh rate: 170mm (max.)

AILERON THROWS

low rate: 55mm downhigh rate: 80mm (max.)

high rate: 80mm up (max.)low rate: 50mm up

ly off. The aileron control surfaces have enough torsion flexibility so that damage to the servosshould not occur.

Flying the Yak 55SP

The Yak has proven to be a very neutral flying airplane. It also maintains a very constant speedin ‘up’ and ‘down’ lines. These two characteristics alone make it a perfect pattern plane, well suit-ed for IMAC up to unlimited class.

It makes a pilot look good. It covers up mistakes. It makes complicated maneouvers easierbecause it flies slowly. Still it's like on rails, even in windy conditions. It does not even know whata knife edge mix means ... it does not need any mixing at all. It’s just "straight"!

Snaps are crisp, and stop immediately. Rolling maneouvers are perfectly on the line, due to themid-wing design. Up and down lines are slow and constant, giving you time to concentrate onthe next move.

Not only for IMAC and high class Pattern, but also for 3D the Yak has its qualities. Large controlsurfaces and low wing loading make it float slowly, yet tumble like crazy at the same time. Thewide wing chord allows a very wide CG range, which means that it can be flown very tail heavy,doing even more exciting manouvers than other planes.

Now, since the engine manufacturers have been much slower than their promises in developinga large giant scale aerobatic engine, we have decided to scale our ultimate Yak 55SP 3.3m downto a span of 3m, making a bold statement in the popular 40% class of aerobatic planes, perfect-ly suited for the reliable and economical 150cc engines on the market today.

We know that many have waited for this move, and we've tried hard to make sure that nobodywill be disappointed. The 3m Yak, just like its bigger and smaller brothers, is one of the best fly-ing planes ever designed. It's a "must have" if you want to be successful in advanced or unlim-ited IMAC.

We hope that you enjoyed building your Yak 55SP. Please let us know if you think that any hard-ware is missing or inadequate. We tried to make this airplane as complete as possible. With goodfeedback from customers you will help us to continue making good things even better. We appre-ciate your comments very much.

Email: [email protected]

Have Fun!Your Composite-ARF Team


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Appendix:Yak 55SP 3m Kit (Version 1.0)

Kit ContentsQuantity Description1 Fuselage1 Wing, right (with servo hatch taped in place)1 Wing, left (with servo hatch taped in place)1 Stab, right1 Stab, left 1 Elevator, right1 Elevator, left1 Rudder1 Cowling1 Protection bag set (fuselage, wings, and stabs)1 Canopy frame1 Wheel pant, right1 Wheel pant, left1 Landing gear, carbon, right1 Landing gear, carbon, left1 Wing tube, 6061 T6 alloy, Ø 50mm x 1035mm.1 Stab tube aluminium Ø 20mm x 435mm.1 Clear canopy2 Elevator hinge, aluminum tube, Ø 4mm x 500mm. (packed in elevators) 1 Rudder hinge, brass tube, Ø 4mm x 600mm (packed in rudder)1 Milled wood/phenolic parts bag1 Hardware bag 1 Instruction Manual (English)

Hardware ListFuselage Pack

Quantity Description4 Allen Bolt M6 x 55mm (engine mounting)12 Washer, M6 , large (engine mounting)4 T-nut, M6 (engine mounting)8 Air vent/Louvre, aluminium (painted to match cowl)8 Allen Bolt, M3 x 12mm (for cowl fixing)8 T-nut, M3 (for cowl fixing)8 Washer, M3 (for cowl fixing)32 Sheetmetal screws, Ø 2.2 x 10mm (for securing air vents)2 Allen bolt, M6 x 20 (to secure top of LG legs)2 Washer M6 (to secure top of LG legs)1 Threaded rod, M3 x 125mm (throttle linkage)1 Clevise, steel, M3 (throttle linkage)1 Nut, M3 (throttle linkage)4 Sheetmetal screws, Ø 2.9 x 13mm (throttle servo)4 Plastic Nut, M6 (wing mounting)2 Silicone tube, 10mm Ø x 150mm long (for mini-pipe bulkheads)4 Allen bolt, M4 x 16mm (canopy frame fixing)2 Allen bolt, M6 x 70mm (wheel axles)2 Nut, M6 (wheel axles)2 Washer, M6 (wheel axles)4 Sheetmetal screws, Ø 2.2 x 10mm (wheelpant fixing)


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Wing Pack (2 sets)Quantity Description2 Allen bolt, M3 x 20 (to secure ball-links to aileron horns)2 Stop nut M3 (to secure ball-links to aileron horns)2 Clevise, aluminum M3, with Pins and E-clips (linkages to servo arms) 2 Nut, M3 (linkages)2 All-thread, M3 x 90mm (linkages)2 Ball-link, M3 (linkages)4 Sheetmetal screws, Ø 2.9 x 160mm (to secure servo hatches)12 Allen bolt, M3 x 12mm (to fix servos to phenolic plates)12 Washer, M3 (to fix servos to phenolic plates)12 Stop Nut, M3 (to fix servos to phenolic plates)16 Sheetmetal screws, Ø 2.9 x13mm (to fix phenolic plates to ribs)1 All-thread, M3 x 65mm (to connect inner two servos)2 Clevise, Aluminum, with pins & E-clips (to connect inner two servos)2 Nut, M3 (linkage between inner two servos)

Stab Pack (2 sets)Quantity Description1 Allen bolt, M3 x 16mm (to secure stabs to spar tube)1 Washer M3 (to secure stabs to spar tube)4 Sheet metal screw Ø 2.9 x 16 mm (to secure servos)1 Clevise, aluminum M3 (with pin and E-clip)1 Ball-Link, M3 (linkage)1 Nut, M3 (linkage)1 All Thread M3 x 75mm (linkage)1 Allen bolt, M3 x 20mm (to secure ball-link to elevator horns)1 Stop nut M3 (to secure ball-link to elevator horns)

Rudder Pack Quantity Description4 Allen bolt M3 x 16 mm (ball-links to servo arms)4 Stop Nut, M3 (ball-links to servo arms)4 Ball link M3 (servo linkages)4 Clevise, steel, M3 (servo linkages)4 Nut, M3 (servo linkages)4 All thread M3 x 45 mm (servo linkages)7 Bolt, M2 x 12mm (to secure rudder phenolic arms to metal discs)7 Nut, M2 (to secure rudder phenolic arms to metal discs)12 Sheetmetal screws, Ø 2.9 x 13mm (to secure rudder servos)2 Allen Bolt M3 x 20mm (ball-links to rudder horns)2 Stop Nut, M3 (ball-links to rudder horns)2 Ball-link, M3 (cables to rudder horns)2 Nut, M3 (to secure threaded ends)2 Threaded ends for Pull-Pull Cables, M32 Pull-Pull Cables 0.9mm Ø, 1.6 metres each4 Crimp tube 2.6 mm. I.D

‘Spare’ hardware pack* This bag contains a few extra items that might be useful in the event of maintenance or repair.

2 Plastic Nut, M6 (wing mounting)2 Ball-links, M32 Phenolic control surface horns2 All-thread, M3 x 150mm2 Allen-bolt M3 x 20mm2 Stop Nut, M31 Allen Bolt M6 x 70mm


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Available Accessories:Tail gear setup with 35mm Ø wheel, size ’XL’. (product #801001)Desert Aircraft DA-150 motor (product #951000)Canister set for DA-150 (product #910150)PowerBox 40/24, dual NiCad crossover unit. (product #960200)PowerSwitch, pair, 20A, for dual NiCads (product #960300)

* Please check our website : www.composite-arf.com, for current availability of options and accessories.


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(above) Complete kit contents of the Butterfly scheme (orange/yellow) #732000

(above) Underside view of the Butterfly Blue/Turquoise scheme.


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Contents of Wing Hardwarepack (2 sets)

Contents of Stab Hardwarepack (2 sets)

(above) Contents of RudderHardware pack

(above) Contents of SpareHardware pack

(above) Contents of Milled wood and Phenolic pack

(above) Contents of Fuselage hardware pack

Mike C, 23rd July 2007. version 1.0

instruction manual composite-arf yak 55sp, 3m · instruction manual composite-arf yak 55sp, 3m tavs...

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